DD.WellWorkover.Cloud/AsbCloudInfrastructure/Services/TelemetryTracker.cs

using AsbCloudApp.Services;
using System;
using System.Collections.Generic;
using System.Linq;

namespace AsbCloudInfrastructure.Services
{
    public class TelemetryTracker : ITelemetryTracker
    {
        private Dictionary<string, DateTime> requests = new Dictionary<string, DateTime>();
        private readonly TimeSpan timeout = TimeSpan.FromDays(7);

        public void SaveRequestDate(string uid)
        {
            requests[uid] = DateTime.Now;
            DeleteOldRequestDates();
        }

        public DateTime GetLastTelemetryDateByUid(string uid) =>
            requests.GetValueOrDefault(uid, DateTime.MinValue);

        public IEnumerable<string> GetTransmittingTelemetryUids()
        {
            DeleteOldRequestDates();
            return requests.Keys;
        }
        
        private void DeleteOldRequestDates()
        {
            requests = requests.Where(dValue => (DateTime.Now - dValue.Value) < timeout)
                .ToDictionary(dValue => dValue.Key, dValue => dValue.Value);
        }
    }
}